Abstract: This paper introduces an In-memory computing scheme based on table lookup in PCM. The hardware system of this scheme consists of control module, connection module and PCM module. In the same PCM array, the lookup table（LUT） with operator results and the address index information of the LUT are mapped. With this scheme, the feasibility of the scheme is verified and evaluated by the calculation of Fast Fourier transform（FFT）. Compared with traditional computing architectures, the new computing architecture has great advantages in power consumption and requires less hardware resources when calculating operations of the same order of magnitude as FFT.